First held in 1960–61 as the Football League Cup, it is one of the three top-tier domestic football competitions in England, alongside the Premier League and FA Cup. It concludes in February, long before the other two, which end in May. It was introduced by the league as a response to the increasing popularity of European football, and to also exert power over the FA. It also took advantage of the roll-out of floodlights, allowing the fixtures to be played as midweek evening games. With the renaming of the Football League as the English Football League in 2016, the tournament was rebranded as the EFL Cup from the 2016–17 season onwards.

The tournament is played over seven rounds, with single leg ties throughout, except the semi-finals. The final is held at Wembley Stadium; it is the only tie in the competition played at a neutral venue and on a weekend (Sunday). Entrants are seeded in the early rounds, and a system of byes based on league level ensures higher ranked teams enter in later rounds, and to defer the entry of teams still involved in Europe. Winners receive the EFL Cup, of which there have been three designs, the current one also being the original. Winners also qualify for European football with a place in the UEFA Europa League – although this place is transferred to the highest-placed Premier League team not already qualified for European competition, should the winner also qualify for Europe through other means at the end of the season. The current holders are Manchester United, who beat Southampton 3–2 in the 2017 final to win their fifth League Cup.

Although the League Cup is one of the four domestic trophies attainable by English league teams, it is perceived as a lower priority cup than the league championship or the FA Cup; the fourth domestic trophy, the Community Shield, is a one-match event. League Cup winners receive £100,000 prize money (awarded by the Football League) with the runners-up receiving £50,000, considered relatively insignificant to top-flight teams, compared to the £2 million prize money of the FA Cup, which is in turn eclipsed by the Premier League's television money (awarded on final league position) and consequent participation in the Champions League.

Some clubs have repeatedly fielded a weaker side in the competition, making the opportunity for giant-killing of the larger clubs more likely. Many teams in the Premier League, Arsenal and Manchester United in particular, have used the competition to give young players valuable big-game experience. However, in 2010, in response to Arsène Wenger's claim that a League Cup win would not end his trophy drought, Alex Ferguson described the trophy as "a pot worth winning".

The original idea for a League Cup came from Stanley Rous who saw the competition as a consolation for clubs who had already been knocked out of the FA Cup. However it was not Rous who came to implement it, but Football League Secretary Alan Hardaker. Hardaker initially proposed the competition as a way for the clubs to make up on lost revenue, due to a reduction in matches played, for when the league was to be re-organised. The re-organisation of the league was not immediately forthcoming; however, the cup competition was introduced regardless.